Unauthenticated OS command injection & arbitrary file upload in Western Digital My Cloud

SEC Consult Vulnerability Lab Security Advisory < 20170307-0 >


title: Unauthenticated OS command injection & arbitrary file upload

product: Western Digital My Cloud

vulnerable version: at least: 2.21.126 (My Cloud), 2.11.157(My Cloud EX2),

2.21.126 (My Cloud EX2 Ultra), 2.11.157 (My Cloud EX4),

2.21.126 (My Cloud EX2100), 2.21.126 (My Cloud EX4100),

2.11.157 (My Cloud Mirror), 2.21.126 (My Cloud Mirror

Gen2), 2.21.126 (My Cloud PR2100), 2.21.126 (My Cloud

PR4100), 2.21.126 (My Cloud DL2100), 2.21.126 (My Cloud


fixed version: -

CVE number: -

impact: Critical

homepage: www.wdc.com/en-um/

found: 2017-01-17

by: Wan Ikram (Office Kuala Lumpur)

Fikri Fadzil (Office Kuala Lumpur)

SEC Consult Vulnerability Lab


An integrated part of SEC Consult

Bangkok - Berlin - Linz - Luxembourg - Montreal - Moscow

Kuala Lumpur - Singapore - Vienna (HQ) - Vilnius - Zurich






Vendor description:


"Reliable, centralized personal storage with automatic backup that plugs into

your own home network. Share whatever you want, anywhere you have an Internet



Source: www.wdc.com/products/personal-cloud-storage/my-cloud.html



Business recommendation:


By combining the vulnerabilities documented in this advisory an attacker

can fully compromise a WD My Cloud device. In the worst case one could steal

sensitive data stored on the device or use it as a jump host for further

internal attacks.


SEC Consult recommends not to attach WD My Cloud to the network until

a thorough security review has been performed by security professionals and

all identified issues have been resolved.



Vulnerability overview/description:


The firmware doesn't apply proper validation on many user inputs. As a

result, below vulnerabilities could be exploited by unauthenticated attackers

to fully compromise the device.


1. Unauthenticated OS Command Injection

Any OS commands can be injected by unauthenticated attackers. This is a

serious vulnerability as the chances for the device to be fully compromise is

very high.


2. Unauthenticated Arbitrary File Upload

A malicious file can be uploaded into the webserver with no authentication

required. It is possible for an attacker to upload a script to issue operating

system commands.


3. Cross Site Request Forgery (CSRF)

There is no anti-CSRF mechanism implemented in the firmware. Due to this, an

attacker can force a user to execute any action through any script. As the

vulnerabilities described in 1) and 2) do not need authentication, those can

be exploited via CSRF over the Internet as well!



Proof of concept:


1. Unauthenticated OS Command Injection

Below is a sample cURL request to execute arbitrary OS command for one of

vulnerable scripts.


$ curl http:// $IP/web/addons/jqueryFileTree.php?host=x&pwd=x&user=x&dir=x&lang=x\"\; <os-command-here>\; echo \"x



2. Unauthenticated Arbitrary File Upload

Below is the cURL request to upload arbitrary files on the webserver.


$ curl -F "file=@shell.php" http:// $IP/web/addons/upload.php?name=x&folder=<target-upload-directory>&index=<script-name>



3. Cross Site Request Forgery (CSRF)

There is no anti-CSRF mechanism implemented for all accessible scripts in the




Vulnerable / tested versions:


The following device & firmware has been tested and found to be vulnerable:

2.11.157 (My Cloud EX2)


As the firmware used by all My Cloud devices are more or less similar, we

believe the other versions are also prone to the same vulnerabilities. This could

be verified by using the IoT Inspector software for automated firmware analysis.



Vendor contact timeline:


2017-01-18: Contacting vendor through "WD Support - Create a Support Case"

page (https://support.wdc.com/support/case.aspx?lang=en).

Assigned ticket number - 011817-11728265.

2017-01-19: Vendor: replies to the ticket asking for more clarification.

2017-01-20: Replied to the vendor, requesting security contact and encryption keys

2017-01-23: Vendor: "we don't have a security department that we could forward

this concern"

2017-01-23: Telling support that there seems to be a security contact by

referencing other WD advisories, requesting security contact again

2017-01-24: Vendor: asking for affected product name and firmware version.

2017-01-24: Providing list of affected product name and firmware versions,

requesting security contact again

2017-01-25: Vendor: informs us that they "have already escalated the case from

their back end team", they will update us.

2017-02-09: Requesting a status update

2017-02-10: Vendor (support): back end team is already informed, they will follow up

2017-02-10: Vendor security contact emails us

2017-02-16: Asking for encryption information to send advisory

2017-02-16: Vendor (security contact): requests security advisory to be shared over

unencrypted channel

2017-02-20: Provided advisory and proof of concept through insecure channel as


2017-02-21: Vendor (security contact): requesting extension of deadline to a period

of 90 days from the date of detail disclosure

2017-02-22: Informing the vendor that we grant extension of disclosure but not from

detail disclosure date (2017-02-20), but from initial contact date

(2017-01-18) as they could have reacted faster in the first place

Set latest disclosure date to 2017-04-19 (no answer from vendor)

2017-03-03: 3rd party researcher discloses many 0-days, containing our findings as

well, www.exploitee.rs/index.php/Western_Digital_MyCloud

2017-03-07: Informing vendor security contact of our public disclosure

2017-03-07: Public disclosure of advisory





There is currently no update available from the vendor.








Advisory URL:







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EOF Fikri Fadzil / @2017